PageRank is a concept created by Larry Page, and he is used by Google search engine. He assigns a rank for a page according to several criteria. To use this tool, you have to enter the website address in the following field and to choose a PageRank style from the following images by clicking on them. Then, click on the "Update" button. You will get an image of your PageRank, the Image URL and the (X)html code to put the Google PageRank Image in your website.
For more information about PageRank, visit this page:
PageRank - Wikipedia